Technical Field
The present invention generally relates to cryogenic refrigerators including a rotary valve.
Description of Related Art
Gifford-McMahon (GM) refrigerators are known as refrigerators that produce cryogenic temperatures. In GM refrigerators, the volume of an expansion space is caused to change by the reciprocation of a displacer in a cylinder. A working gas is caused to expand in the expansion space by connecting the expansion space selectively to the suction side or the discharge side of a compressor in accordance with a change in the volume of the expansion space. A rotary valve may be used to switch the connection of the expansion space between a connection to the suction side and a connection to the discharge side.